use a net.UDPConn in fakeClosePacketConn

[marten-seemann]

Caddy should use a *net.UDPConn instead of a net.PacketConn in

caddy/listeners.go

Lines 205 to 210 in e2940c8

	type fakeClosePacketConn struct {
	closed int32 // accessed atomically
	usage *int32 // accessed atomically
	key string
	net.PacketConn
	}

This will allow quic-go to set the receive buffer size, see https://caddy.community/t/udp-receive-buffer-size-quic/11244 and quic-go/quic-go#3024.

[francislavoie]

Is that safe to change though? Does that code path use TCP too? 🤔

[marten-seemann]

I don't think that's possible. net.TCPConn doesn't implement net.PacketConn.